Decanting apparatus.



PATENTED 001 5, 1907.

. N. DORR.

J. v I I DEGANTING APPARATUS. APPLICATION FILED FEB. 2B, 1907.

JonN v. N. norm, or LEAILISOUTH DAKOTA;

nncmme. arrsnarus.

To all whom it may concern:

Be it known that I,'JorrN V. N. Done, a citizen of the United States,residing in the city of Lead, in the county of Lawrence and State ofSouth Dakota, have invented certain newand useful Improvements inDecanting Apparatus, I of which the following is a specification;

In the wet treatment or ores, as by the cyanid process, the pulp passingfrom the ore pulverizers consists of cyanid solution or water, sands,and what are known as slimes", consisting mainly ofamorphous orflocculent matter derived from the or earthy material of the ore. Thispulp is usually first treated -in classifiers to separate the-sandsfromthe slime's and the sands are conveyed to vats and leached in cyanidsolution -while the slimes are separately treated. It is not practicableto leach -or otherwise treat the sands and slimes together, as theslimes' so choke the material in the leaching-vats as to prevent freepercolation.

Slimes coming from a classifier of any sortusually I consist of ten ormore of solution or waterto one of solidsand asa preliminary step to allp for the recovery of values from theslimes it is n f peated. Forthiswork flat bottomed to remove as much of the solution or water aspossible and thicken the slimes until they carry between one part'andthree parts of l'quid to one part of dry slinies. This separation isusually done in vats or cones by intermittent or continuous demntstionIntermittent dem ntstion consists in filling a largevat with the thinpulp and than allowing it to stay until settled to thi k pulp and offthe clear solution from the top after'which the thiclrened slimes areusually sluiced additional solution no values into another .vat andthereby diluted, whereupon theyare allowed to'settle again and theprocess revats are commonly used as'the solid slimes are washed. out bythe additional water or solution ,used. In intermittent deeantation,much time is lost-in recovering the last portion of the yolution; whichtime only a small part of the decanting vessel is-utilised,- making alarge installation-n for a comparativelysmall amount of work.Ineontinuo'us 'decantation, on

the other; hand, either large cones are used or a flat bottomed tan]; isallowed to'fill up with slimes until it forms a natural cone; Thickenedslinres are fed into it continuously and solution overflows from the topof the vat at all times, while the thickened slimes are drawn out fromthe bottom continuously, or at comparatively short intervals. Whensingleor mul tiple cones or vessels having conical bottoms have beenemployed'for continuous deeantation, it ha been found difficult tosecure uniform and continuous working owing to the tendency of thesolids to collect on the slopes and then suddenly slide down towardsSpecification of Letters Patent. Application filed February 26,1907.Serial a. 869,897.

at the top with a launder into which.the liquid de :reference to' thedischargeopening.

,Patnted Oct. 1 5, 1907.

the discharge opening of the vessel, thereby agitating the partiallysubsided material and choking the discharge opening unless an extremelylarge amount of the liquid desiredto be separated is allowed to go outwith the solids and even this expedient is not always successful,especially when the slimes are in cyanid solutions where the slimes tendto flocculate and solidify, thus requiring the attendant to scrape upthe material to prevent the cone from filling with solid slimes andreducing the settling capacity to a great extent. The object of myinvention is to separate by a decanting process, slimes and similarmaterial from the liquid containing themby a rapid and eificientoperation. l According to my invention, I pmvide a decanting vessel orsubsidence tank to which the liquid carrying the slimes is continuouslyfed and which is provided cants while the solids or slimes subside orbecome 'ckenedby gravity. A discharge opening is formed in the bottom ofthe tank and flights or scrapers are moved over the thickened materialand direct it gently and continuously the discharge opening of thedecanting vessel so as not to interfere with the subsidence of theinooming'msterial but prevent it settling to the solid condition. Thebottom of the tank may be hat or horizontal or it may be slightlyinclined towards, the discharge opening. Preferably I provide the vesselv with a flat or horizontal bottom and allow the material to pile uptheregnjofornpgbed redeivewthehaterial as first as it'is deposited fromthe incoming pulp.

Each preferably comprises an arm carrying aseriesofscxaperplatesorflightsandeachsuchscmper arm is preferablyarranged to extend radially in an up wardly and outwardly inclined linefrom the discharge opening toward'the side of the tanlr'and the scraperplates or flights are set at such an angle to the arm as, when thearm'is rotated, to scrape the thickening material 06 from the inclinedtop of the slime bed and niove it into the discharge opening withoutagitatingthe liquid or interfering with the settling of materialtherefrom. 1

drawn off from the bottomof the hopper either continuously orintermittentlywithout drawing ofl' much of the liquid. The scrapers arecarried'by devices which can be raised and lowered readily to entirelyremove the scrapers from the settling vessel if desired or to adjustthem to any desired elevation.

The scrapers may be placed at any desired angle with The dischargeopening is provided with a cone or .hopper which receives the slimes'which latter may be iio . .'In the accompanying drawings: Figure 1showsa verbodying my improvements. Fig. 2 shows a sectional planthereofon the line 2 2 of Fig. l.- Fig. 3 illustrates .a modification.

The tank or vessel, A, is preferably made of large diameter, butisrelatively shallow. For instance, it may have a diameter of 35 ft whileits depth need not be over 12 ft. Such dimensions have proved correctand efficient in practice, but I have also done good-work with a tankhaving a depth of only 6 it. A launder, B, is provided at the upper edgeof the vessel. Preferably this, is made annular, as shown, andisprovided with a discharge pipe, ll. The liquid containing the slimesis led in through a spout, B'-', or it may be fed in any other suitableway. Any suitable frame, A, may be employed to support the vessel, A;

A discharge openingis provided'in the center of the, tank. which is ofsuitable dimensions and is provided with a cone, G, extending downwardlyfrom the open-:

in a supeistrm-ture or' upper frame, E. The shaft, D,

has a tongue and groove connection with a worm wlieel, F, mounted instationary bearings in the frame, E, and driven by a worm, F, which maybe operated in 'any suitable way either by hand or by power. Theconnection between the shaft, D, and the. wheel, F, is such that theshaft may be raised or lowered to-any desired extent, but is made torevolve with the wheel when the latter is rotated. At its upper end theshaft, D, is screw-tln'eaded and carries a nut, D, below which-isarianged a bearingblock, G, having a ball-bearing, G,- on a part, H,resting on the frame, E. Any suitable means may be connected with thepart, H, for raising and lowering the shaft.

The bottom of the 'decanting vessel may be flat or horizontal, as shownin Fig. 1, or itmay beinclined as shown in Fig. 3.' Where the bottom ofthe decanting vessel is flat or horizontal or has a gradual incline, itis necessary to provide some means for scraping-the deosited materialfrom the bottom and directing it to-- wards lllt discharge opening ofthe vessel. The form of scraper which-I prefer is that illustrated.

In general .each scraper. comprises a-scraper arm exiending upwardly andoutwardly from the center of the discharge opening toward the side ofthe tank in a radial line and carrying a series of scraper plates orflights which are setat. such an angle to the arm which carries them as,when the arm is rotated, to cause the thickcning material to be scrapedoff fromthe inclined top of the slime bed and moved into the dischargeopening without agitating the liquid or interfering with the settling ofmaterial therefrom.

I preferably employ four radial series of flightsbut this number may bevaried. In the particular arrangement shown, each series of flights,J',-is carried by a radial arm, K, attached to the vertical shaft, D.Each shall. by an upwardly inclined brace-rod, L, which may be securedto the shall in the manner shown and may "of the arm.

be adjusted thereon to correspond with the inclination The scrapers maybe arranged on horizontal arms so as to scrape the material from thehorizontal bottom of the decanting vessel, but preferably I allow theslinies to collect and form a bed, X, on the bottom of the vessel andincline the scrapers upwardly-and outwardly in the manner. beforespecified and as illustrated in Fig. 1, so

as to form a bed of slime-which increases in depth outwardly from thecentral discharge opening, forming an inclined upper surface slopingdownwardly towards the discharge opening. 1 The scrapers remove theslime from the top of this bed and direct it towards the center ofthetank. These scrapers are moved very slowly. In

a tank of the dimensions before specified, viz: one 35 ft.

in diameter, the scrapers are preferably made to revolve one-fifth ofa'revulution pe'rminute. This will serve to remove the slimefrom the bedfast enough but without causing any such agitation in the liquid aswould interfere with the subsidence of the contained solid material.- av I In order to prevent solid matter from adhering to the cone, 0, I mayprovide oneor more scrapers, M,- which revolve with the scrapers, J andact upon the cone in themaimer clearly indicated. The thick pulpreceived by the cone, C, allowed to accumulate therein and is removed atintervals or; the discharge from the cone may-be suchas to becontinuous, the thickness of the slime discharged being regulated bythe'amount drawn out through the discharge opening.

' It will be understood that where decanting vessels with steeplyinclined bottoms are employed, there is constant danger of anobjectionable agitation of the liquids when the slimes, afteraccumulating-on the steeply inclined bottoms, separate therefrom andfall; rapidly downtothe discharge opening of the vessel. Furthermore, insuch apparatus, it is necessary to employ a plurality of decantingvessels in order to pro- -vide sufiicient area for settling. In mypresent apparatus, the vessel ismade very wide inorder to provide such asettling area. The bottom may be made horizontal or only slightly inclined so as to avoid the agitation of the liquid by the falling of theslimes, while the slim'es, as fastas required, are detachtsl fronr thebottom of the vessel and moved downwardly to the discharge openingwithout interfering with the settling operation. l v I have described myapparatus as being especially intended to separate. slimcs in a cyanidprocess, but it will be understmkl that this apparatus may be employedfonseparatingsother solid matter from liquid in various processes. 1have shown the best form of apparatus known to me for carrying out myinvention and one which has. been found to be efficient in operation butthe construction of the'apparatus may be varied without departing fromthe novel features of my improvements. I

The discharge opening and its cone or hopper may be considered merely adepression in the bottom of the de- 'eanting vessel into which thesettled material passes discharge opening of the reference to the armwhich carries them.

3 A decanting apparatus comprising a settling or subsidence vesselhaving at the top a launder "for receiving the decanting liquid and adischarge opening in the bottom and a scraper comprising a radial armand flights carried inclined direction with reference to the dischargeopening of the vessel and set at an angle with reference to the armwhich carries them.

4. The combination of a decanting vessel having a -ing it towards saiddepression. 7

5. The combination of a decanting vessel having a launderat the top forreceiving the decanting liquid, a depression for receiving the solidmaterial and a scraper comprising a series of flights moving across thebottom of the vessel and carrying the settled material towards thedepression thereof. 7 l p 6. The combination of a decanting vesselhaving a substantially flat bottom on which a bed of solid material isdeposited and provided with a depression for receiving thesettlingmaterial and a'scraper comprising flights arranged in seriesradially in an upwardly and outwardly inclined direction and engagingthe top of .the bed to remove the thickened material therefrom anddirect it towards the depression. I

The combination of a'decanting vessel having a substantially horizontalbottom and provided with a central depression for receiving thethickened material, a revolving scraper in said depression and arevolving scraper extending across the.bottom of the tank for collectingthe thick slime and moving lt'towards the central depression I of thevessel.

In testimony whereof, I have hereunto subscribed my name.

JOHN V. N. DORR.

. Witnesses:

WILLIAM MAXIMER, Jr.,

MARSHALL S. WALKER.

